Process and device for treating the surface of large objects

ABSTRACT

A process and device are disclosed for cleaning the surface of airplanes (44). A large manipulator arranged on a truck (10) is moved towards the airplane (44) up to a predetermined position within its range of action and is parked in that position. A rotary brush bearing head (18) is moved over the surface of the object by means of an articulated mast (13) arranged on the truck (10) and constituted of several extension arms (12, 12&#39;, 12&#34;, 12&#39;&#34;, 14) that may swivel or move with respect to each other at turning knuckles and/or prismatic joints and of a multiple joint (16) arranged at the last extension arm (14). In order to carry out a washing process in a reliable manner, without risk of collisions even when the large manipulator is not accurately positioned in front of the airplane (44), the large manipulator is parked within a limited two-dimensional parking field (46) spaced apart from the airplane (44), while the joints (20 to 26) of the articulated mast (13) and/or the multiple joint (16) are controlled during the surface treatment according to a series of predetermined sets of joint coordinates associated to the actual position of the large manipulator within the parking field (46), and the brush bearing head (18) is moved along a predetermined path of operation over the surface of the object.

FIELD OF THE INVENTION

The invention relates to a process for treating, in particular forcleaning, the surface of large objects, such as airplanes, ships,buildings, in which a large manipulator arranged on an undercarriage ismoved into a specified position toward the large object and is parkedthere, and in which a tool, preferably designed as a rotating brushhead, is moved over the surface of the object by means of an articulatedmast. The mast is arranged on the undercarriage and consists of severalarms, which are pivotal or movable with respect to each other on pivotand/or thrust points, and, if necessary, a multiple joint is arranged onthe last arm. Furthermore, the invention relates to an arrangement foraccomplishing this process.

BACKGROUND OF THE INVENTION

The DE-A-4035519 already suggests to equip a large manipulator with aremote-controllable brush head. The known large manipulator has anarticulated mast, which can be assembled of several arms pivotal withrespect to one another at their ends, the base arm is rotatablysupported about a vertical axis on a bearing block arranged on amotor-driven undercarriage, and the last arm has a multiple joint, whichcan be equipped with the brush head. From this reference it is alsoknown to provide the brush head with sensors, which enable a automaticcontrol of the brush head relative to the surface to be treated inaccordance with a sensor signal originating at the sensor during thecleaning operation and can be outputted.

The basic purpose of the invention is to develop a process and anarrangement of the above-disclosed type, with which in the case of aninexact positioning of the undercarriage carrying the large manipulatorin front of the large object to be treated and also in the case ofsurfaces having a complicated design, a collision-free fully automatictreatment is possible.

To attain this purpose the characteristic combinations disclosed hereinare suggested. Advantageous embodiments and further developments of theinvention result from the dependent claims.

SUMMARY OF INVENTION

The solution of the invention is based on the thinking that in the caseof an inexact positioning of the undercarriage, first it is necessary todetermine the actual station coordinates, and then a movement programfor the joints of the articulated mast and/or the multiple joint, whichprogram relates to the actual station coordinates, is to be set up.Accordingly, the invention suggests that the undercarriage is stationedwithin a limited two-dimensional parking field spaced from the largeobject to be treated, and that the joints of the articulated mast and/orof the multiple joint are controlled during the surface treatment inaccordance with a series of joint-coordinate sets associated with theactual position of the large manipulator within the parking field, andthe tool is thereby moved along a specified operating path over thesurface of the object.

A preferred embodiment of the invention provides thereby that theparking field is divided by a limited two-dimensional distance grid,that for each grid point of the distance grid there is specified aseries of joint-coordinate sets defining the support points of theoperating path of the tool stored as a joint-coordinate data file in adata bank of a data-processing system, and that the position-referencedjoint coordinate sets, preferably through interpolation from thejoint-coordinate data files stored in the data bank, are calculated inaccordance with the actual position of the undercarriage within thedistance grid and are stored in the working data file, prior to startingthe surface treatment by using the joint-coordinate sets selected fromthe working data file and, if necessary, additional movement-referencedparameters. The joint-coordinate sets selected from the working datafile can follow in accordance with sensor signals preferably extractedat each support point of the operating path. For this purpose it is, forexample, possible to measure the frictional or torsion resistance or thebearing pressure engaging the tool and to read same as a sensor signalfor the guiding of the joint coordinates. Accordingly, it is alsopossible to measure other physical sizes, for example the distance ofthe tool from the object or a variable inclination of the largemanipulator resulting from the deformations of the substructure, and toread same as a sensor signal. Also, in order to avoid during the guidingof the joint coordinates undesired collisions, it is advantageous tocheck the actual joint coordinate sets with respect to freedom fromcollisions through a comparison with joint coordinates stored withrespect to adjacent grid points of the distance grid taking intoconsideration specified tolerance limits.

In a preferred arrangement for carrying out the process of theinvention, in which the large manipulator has an articulated mast, whichconsists of several arms pivotal with respect to one another on pivotjoints by means of hydraulic or motorized driving systems and rotatablysupported with its base arm about a vertical axis on a pivot-bearingblock of a motor-driven undercarriage, and has a tool preferablydesigned as a rotating brush head and arranged on the last arm of thearticulated mast or on the free end of a multiple joint arranged on thelast arm and having several thrust and/or pivot joints, it is suggestedin order to attain the above-disclosed purpose that an opto-electronicdistance camera, which can be aligned with the large object to betreated, is arranged on the undercarriage, and a calculator-supportedevaluating electronics, which is loaded with the distance-image signalsof the distance camera, is provided as an aid for moving andpositioning, and for locating the large manipulator relative to thelarge object to be treated. The distance camera is therebyadvantageously arranged rigidly or movably, in particular, pivotallyabout a vertical axis and/or inclinable about at least one horizontalaxis on the large manipulator in the vicinity of the pivot-bearingblock.

In order to create an association between the coordinates determined bythe distance camera and the tool coordinates of the articulated mast,the evaluating electronics has, according to the invention, a programpart for normalizing the joint coordinates of the articulated mast inaccordance with the tool coordinates measured directed and the aboveelectronic camera relative to a stationary, preferably cubic calibrationmember. Errors in the position of the large manipulator due todeformations of the arms, zero-position offset of the angle and pathreceiver and torsions in the substructure of the articulated arm and ofthe undercarriage are detected during this normalization.

The evaluating electronics has furthermore advantageously a storagearrangement for storing the reference-image data of marked sections ofthe large object viewed from a specified parking field and a softwareroutine for comparing the distance-image data taken by the distancecamera with the large manipulator positioned in front of the largeobject within reach of the articulated mast with the reference-imagedata with a coordinate-like association of the large manipulatorposition within the specified limited parking field. The parking fieldis advantageously divided by a two-dimensional distance grid, wherebywith each grid point of the distance grid is associated ajoint-coordinate data file or a movement program within a data bank, inwhich a series of joint-coordinate sets of the articulated mast along aoperating path to be travelled by the tool on the surface of the objectis stored.

In order to measure the joint coordinates a coordinate receiverpreferably in the form of an angle or path receiver, is associated witheach joint of the articulated mast and, if necessary, of the multiplejoint at the output of which receive the respective joint coordinate canbe read.

The evaluating electronics has advantageously a program for calculatingand storing a series of position-referenced joint-coordinate sets, whichseries is designated for the treatment operation, through interpolationfrom the stored joint-coordinate sets in accordance with the deviationof the actual position of the large manipulator from the next grid pointwithin the specified distance grid.

To carry out the treatment operation, the evaluating electronics has acalculator-supported circuit part for controlling the drive systems ofthe articulated-mast joints in accordance with the deviation of thejoint coordinates instantaneously read at the coordinate receivers fromthe associated values of the stored joint-coordinate sets. In order tobe able to compensate for tolerance deviations, the tool has a sensor,which reacts to the distance from the surface to be treated, to itstreatment resistance or to its depth of penetration into the surface tobe treated, whereby correcting signals can be derived from the sensorsignal in order to have the driving systems of the articulated-mastjoints follow.

In order to, in addition, be able to compensate for deformations in thesubstructure of the large manipulator during the washing operation, atleast one inclination indicator is associated with the pivot and/orinclination axes of the distance camera, from the output signals ofwhich inclination indicator can be derived the correcting signals inorder to have the driving systems follow.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be discussed in greater detail hereinafter inconnection with one exemplary embodiment, which is schematicallyillustrated in the drawings, in which:

FIG. 1 is a side view of a movable large manipulator with a brush headfor washing of airplanes in a collapsed position;

FIGS. 2a and 2b are two diagrammatic illustrations of the largemanipulator in an operating position in front of an aircraft;

FIG. 3 is a top view of the grid-like parking field for the largemanipulator according to FIGS. 2a and 2b.

DETAILED DESCRIPTION

The mobile large manipulator illustrated in FIGS. 1 and 2 consistsessentially of an articulated mast rotatably supported with its base arm12 about a vertical axis on a pivot-bearing block 11 of a motor-drivenundercarriage 10, a multiple joint 16 arranged on the last arm 14 of thearticulated mast 13 and a brush head 18 releasably fastened to the freeend of the multiple joint. The five arms 12, 12', 12", 12'" and 14 ofthe articulated mast 13 are connected with one another at their endsfacing one another limited pivotally about horizontal axes at joints 20,22, 24, 26. The pivoting is done by means of hydraulic cylinders 27,which are arranged between the arms at suitable points. The base arm 12is supported pivotally on the pivot-bearing block 11 on a horizontalbearing 28 by means of a hydraulic drive 30. This arrangement makes itpossible to cover with the brush head 18 any desired surface contourswithin the plane defined by the arms. With the help of the multiplejoint 16, which can be adjusted by a motor, it is additionally possibleto move the brush head 18 in six degrees of freedom about several pivotand thrust axes relative to the last arm 14.

In the area of the pivot-bearing block 11 there is arranged anopto-electronic distance camera 40 in the form of a 3-D laser scanner,which detects a three-dimensional space within the viewing window 42 anddigitalizes same with respect to the distance from an object ofmeasurement 44. The distance camera 40 is arranged at a sufficientheight above the undercarriage 10, in order to be able to measuresignificant areas of the object of measurement 44 from the viewingwindow 42. The distance camera 40 works with a laser beam which is movedwith a specific cycle frequency through the opening angle of the viewingwindow 42. The evaluation of the distance signals, which result from atime-difference measurement, permits the recognitional whether and atwhat distance a reflecting surface exists.

In order to adjust the distance measurement with the distance camera 40and the deflection of the articulated mast 13 taking into considerationthe various articulated-mast configurations to one another, anormalization of the manipulator with respect to the distance camera 40is necessary. The zero positions of the manipulator axes of joints 20,22, 24, 26 and of bearing 28 are fixed during the normalization. Thesezero positions are determined through a closed kinematic chain, which,using a measuring cube, brings the measured results of the distancecamera into relationship with the deflections of the articulated mast.The measuring cube is thereby oriented such that with the distancecamera 40 a corner is located and this corner is used as a referencepoint for the positioning of the last arm 14 of the articulated mast 13.The angular positions of the joints during a plurality ofarticulated-mast configurations are hereby determined. From this resultparameters for a set of equations based on which the coordinatetransformation between the electronic camera 40 and the manipulator 13can be determined. The zero positions of the individual joints aredetermined with these measurements, taking into consideration thedeformations in the individual arms (12, 12', 12", 12'", 14), whichright from the start cannot be exactly defined. The measurements arecarried out at various distances in the measuring cube by the distancecamera 40 in order to take into consideration the various constellationsof the manipulator in consideration of the zero-position errors and ofthe deformations and of the orientation of the distance camera 40relative to the manipulator system.

In order to move the large manipulator into a washing position in frontof the aircraft 44, it must be put into a definite position during thecourse of the starting operation so that all surface areas to be coveredduring a washing program lie within the reach of the articulated mast 13with the washing brush 18. In order to avoid unnecessary complicationsduring the starting and positioning of the large manipulator, a parkingfield 46 with a diameter of approximately 4 m is defined in each washingposition, which in turn is divided into a rectangular grid with a gridspacing of 40 cm between the individual grid points 48. The grid spacingmust thereby be no more exact than the exactness of the object to bemeasured. It is to be considered thereby that in the case of aircrafts,already due to tolerances between the individual models of a specifictype and due to different loads and temperature conditions, differencesin measurement of 50 cm and more can result.

The image data produced through the distance camera 40 is evaluated inan evaluating circuit and an on-board calculator. A significant sectionof the airplane 44 is stored with reference to the viewing window 42 ofthe distance camera 40 as a reference image in a storage medium of theon-board calculator for each type of airplane to be worked and for eachparking field 46 to be controlled. The distance camera continuouslyproduces a distance image of the respective airplane section as an aidfor moving into the parking field 46 and compares said image with thestored reference image. Direction and position data can be derivedtherefrom, which give the driver instructions for the direction oftravel and the distance. Also, it is basically possible to convert thedeviating signals resulting from this directly into driving and steeringsignals for the undercarriage. Goal of the aid for moving is to positionthe large manipulator on the parking field 46 within reach of theairplane 44 and to orient same with respect to the course angle. Afterreaching the parking field 46, the undercarriage 10 is supported on theground by swinging out and by lowering the support legs 50 and is thuspositioned relative to the airplane.

The large manipulator can then be adjusted, namely its position withinthe grid field 46 and the orientation relative to the airplane 44 can bedetermined. This is also done with the help of the distance camera 40through comparison with a stored reference sample. Since the distancecamera is arranged at the articulated mast 13, it must be assured thatits position is also considered when determining the course angle. Afterthe adjustment, the inclination indicators are detected at the distancecamera 40 and are set to zero. The relative angle is then considered inthe movement program during a movement of the articulated mast 13 basedon the inclination of the base.

Artificial set-up points 1 to 109 are then determined by the grid field46, for each of which an offline (thus on an external calculator)created complete washing program is stored. A plurality of data sets,which define the angular positions of each joint, are stored aswashing-program data (joint coordinate sets). Several such jointcoordinate sets form a working path 52 along the airplane surface, whichdefine the geometric location of the brush head during the washingoperation. The washing program is checked on the external calculatorsuch that no collision with the object, or possibly existing docks, orhall parts can occur. The distance between the individual coordinatesupport points is on the average 30 cm on the airplane surface. Theexact position of the distance camera 40 with respect to the airplane 44is now determined during the adjustment and thus the exact spot withinthe grid field 46. The joint coordinates are then recalculated from thenext-lying grid point 48 by interpolation to the actual base. These dataare stored in a data file in the operating store of the manipulatorcontrol as the actual washing program before the washing program isstarted through the manipulator control. Furthermore, the collisionspace of the individual joints is determined through the four adjacentpoints 48 within the grid field 46 and the permitted tolerances of, forexample, ±50 cm. These four adjacent points, converted into jointcoordinates, thus describe the space, in which the ends of thearticulated-mast arms are permitted to move.

When these preparations have been made, the actual washing operation canstart. The articulated mast is for this purpose unfolded through anunfolding program. By successively recalling the joint coordinates fromthe operating data file desired-values are obtained, which are reachedby the washing brushes, whereby the actual and desired value comparisonat each individual joint occurs through the associated coordinateindicator. Because of deformations of the airplane and of thesubstructure, inexactnesses of the process, and dynamic errors of thedevice, a fine tuning must be carried out. In order to achieve thedemanded washing result, the manipulator must be moved with an exactnessof approximately 10 mm with respect to the prescribed penetrating depthof the washing brush into the surface. This can only be achieved with anadditional sensory mechanism, which compensates for the mentioned errorsby measuring the bearing pressure and by supplying the auxiliary axes ofthe multiple joint 16. The auxiliary axes are telescopic axes, whichcompensates for position errors and, about a pivot axis, the orientationerrors of the brush head.

It is basically possible to permit the distance camera 40 to also runduring the course of a washing program and to utilize same formonitoring collisions. The distance camera 40 can hereby measureindividual joints and the airplane and control these preventingcollisions. This could be important if, for example, a measured-valuereceiver at one of the joints breaks down and delivers incorrectmeasured values, which are not recognized by the operator and by thecalculator.

In conclusion the following is to be stated: The invention relates to aprocess and an arrangement for the surface cleaning of airplanes 44, inwhich a large manipulator, which is arranged on an undercarriage 10, ismoved into a specified position within the reach of the airplane 44 andis there parked, and in which a rotating brush head 18 is moved over thesurface of the object by means of an articulated mast 13, which isarranged on the undercarriage 10 and consists of several arms 12, 12',12", 12'", 14, which are pivotal or movable with respect to one anotheron pivot and/or thrust joints, and a multiple joint 16 arranged on thelast arm. In order to guarantee a reliable and collision-free washingoperation even during an inexact positioning of the large manipulator infront of the airplane 44, the large manipulator is stationed within alimited two-dimensional parking field 46 spaced from the airplane 44,whereas the joints 20, 22, 24, 26 and the bearing 28 of the articulatedmast 13 and/or of the multiple joint 16 are controlled during thesurface treatment in accordance with a series of joint-coordinate setsassociated with the actual position of the large manipulator within theparking field 46. The brush head 18 is thereby moved along apredetermined operating path over the surface of the object.

We claim:
 1. A process for treating a surface of large objects,comprising the steps of moving a large manipulator arranged on anundercarriage into a parking position within reach to the large object,while in the parking position positioning the undercarriage spaced fromthe object in a two-dimensional parking field having a specifiedboundary to define an actual parking position, determining the positionand orientation of the large object with respect to the actual parkingposition of the large manipulator, moving a treatment tool over thesurface of the large object along a specified working path associatedwith the actual parking position of the large manipulator by means of anarticulated mast which is arranged on the undercarriage and consists ofseveral arms, pivoting the arms with respect to one another on pivotjoints, treating the surface of the object with the treatment tool, andcontrolling the joints of the articulated mast during the surfacetreatment in accordance with a series of specified joint-coordinatesets, which series is associated with the actual parking position of thelarge manipulator within the parking field.
 2. The process according toclaim 1, further comprising the steps of taking a distance image of aspecified section of the large object to be treated with anopto-electronic distance camera while approaching the object, comparingthe distance image to a reference image of the specified section storedin a memory device to determine deviations, and converting the resultingdeviations into one of steering signals when the undercarriage isoutside of the parking field and position-determining locating signalswhen the undercarriage is within the parking field.
 3. The processaccording to claim 1, further comprising the steps of dividing theparking field into a two-dimensional distance grid having grid points,specifying the series of joint-coordinate sets defining the supportpoints of an operating path of the tool for each grid point, storing theseries of joint-coordinate sets as a joint-coordinate data file in adata bank of a data-processing system, and storing the joint-coordinatesets corresponding to the grid point at which the undercarriage isparked in a working data file before the treatment of the surface istriggered using the joint-coordinate sets selected from one of theworking data file and additional movement-referenced parameters.
 4. Theprocess according to claim 3, further comprising the steps ofinterpolating the position-referenced joint-coordinate sets from thejoint-coordinate data file stored in the data bank in accordance withthe actual position of the large manipulator within the distance grid,and storing the interpolated position-referenced joint-coordinate setsin the working data file.
 5. The process according to claim 3, furthercomprising the steps of measuring the position of the articulated arm bysensors producing sensor signals, and comparing the sensor signalsmeasured at each support point along the working path with thejoint-coordinate sets selected from the working data file to determinethe actual path of the articulated arm.
 6. The process according toclaim 5, wherein the step of measuring the position of the articulatedarm includes measuring at least one of frictional resistance, torsionresistance and bearing pressure experienced by the treatment tool. 7.The process according to claim 5, wherein the step of measuring theposition of the articulated arm includes the steps of measuring thedistance of the tool from the large object without contact and producinga sensor signal corresponding to the distance measurement of the toolfrom the large object.
 8. The process according to claim 5, furthercomprising the steps of measuring the inclination of the largemanipulator with respect to one of a substructure supporting theundercarriage and the object, and outputting the measured inclination asa sensor signal.
 9. The process according to claim 5, further comprisingthe step of comparing the joint-coordinate sets guiding the arm tojoint-coordinates stored with respect to adjacent grid points takinginto consideration specified tolerance limits of arm movement to preventcollisions between the arm and at least the object.
 10. An arrangementfor treating a surface of large objects positioned adjacent a parkingfield, comprising a large manipulator having an articulated mast, anundercarriage and a pivot-bearing block positioned on the undercarriage,the articulated mast consists of several arms pivotally connected to oneanother at pivot joints by means of hydraulic or motorized drivingsystems and is rotatably supported by a base arm of the several armsabout a vertical axis on the pivot-bearing block, a drive means forpivoting respective ones of the arms about the pivot joints, a treatmenttool arranged on a last arm of the articulated mast for treating thesurface of the large object, an opto-electronic distance camera arrangedon the large manipulator and alignable with the large object to betreated producing distance image signals measured to the large object,and an electronic means receiving the distance-image signals of thedistance camera for aiding in one of positioning the undercarriage andlocating the large manipulator relative to the large object to betreated, the electronic means having a storage arrangement for storingreference-image data of the large object viewed from the parking fieldwith a specified boundary arranged spaced from the large object, and asoftware means for comparing distance-image data from the distance imagesignals taken by the distance camera when the large manipulator ispositioned so that the articulated mast reaches the large object withthe reference-image data to determine a coordinate positioning of thelarge-manipulatorwithin the parking field.
 11. The arrangement accordingto claim 10, wherein the distance camera is arranged pivotally about avertical axis and inclinable about at least one horizontal axis on thelarge manipulator adjacent the pivot-bearing block.
 12. The arrangementaccording to claim 10, wherein a coordinate indicator is connected toeach joint of the articulated mast, the coordinate indicator measuringone of the angle of the arms at the joint and the path of the joint andoutputting a joint coordinate signal.
 13. The arrangement according toclaim 12, wherein the distance camera outputs a tool coordinate signalcorresponding to the measured distance of the tool, and wherein theelectronic means has a calculator-supported circuit for normalizing thejoint coordinate signal with the tool coordinate signal relative to astationary, cubic calibration volume.
 14. The arrangement according toclaim 10, wherein a data bank stores at least one of a joint-coordinatedata file and a moving program, and wherein the parking field is dividedby a two-dimensional distance grid defining grid points, each grid pointwithin the distance grid is associated with one of the joint-coordinatedata file and the moving program, and the joint-coordinate file stores aseries of joint-coordinate sets of the articulated mast along anoperating path to be travelled by the tool for treating the surface ofthe object.
 15. The arrangement according to claim 14, wherein theelectronic means has a software means for calculating and storing aseries of joint-coordinate sets for effecting the treatment operation byinterpolation of the stored joint-coordinate sets according to thedeviation of the actual position of the large manipulator from theadjacent grid point within the distance grid.
 16. The arrangementaccording to claim 14, wherein the electronic means has a means forcontrolling the drive means of the articulated-mast pivot joints inaccordance with the deviation of the joint coordinates measured by thecoordinate indicators from the associated values of the storedjoint-coordinate sets.
 17. The arrangement according to claim 14,wherein the tool has a sensor means for measuring one of the distancefrom the surface to be treated, operating resistance of the tool, andpenetration depth of the tool into the surface to be treated, the sensormeans producing an output signal received by the electronic means, andthe electronic means deriving correction signals for controlling thedrive means of the articulated-mast joints.
 18. The arrangementaccording to claim 14, wherein at least one inclination indicatormeasuring deformations in a substructure supporting the largemanipulator is associated with at least one of the pivot and inclinationaxes of the distance camera, the inclination indicator producing outputsignals received by the electronic means, the electronic means derivingcorrecting signals from the output signals for controlling the drivemeans of the articulated-mast joints.
 19. The arrangement according toclaim 10, wherein a multiple joint having multiple degrees of freedom ofmovement is arranged on the last arm of the articulated mast, and thetreatment tool is a rotating brush head positioned on the multiplejoint.